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Message-ID: <20250407234223.1059191-2-nphamcs@gmail.com>
Date: Mon, 7 Apr 2025 16:42:02 -0700
From: Nhat Pham <nphamcs@...il.com>
To: linux-mm@...ck.org
Cc: akpm@...ux-foundation.org,
hannes@...xchg.org,
hughd@...gle.com,
yosry.ahmed@...ux.dev,
mhocko@...nel.org,
roman.gushchin@...ux.dev,
shakeel.butt@...ux.dev,
muchun.song@...ux.dev,
len.brown@...el.com,
chengming.zhou@...ux.dev,
kasong@...cent.com,
chrisl@...nel.org,
huang.ying.caritas@...il.com,
ryan.roberts@....com,
viro@...iv.linux.org.uk,
baohua@...nel.org,
osalvador@...e.de,
lorenzo.stoakes@...cle.com,
christophe.leroy@...roup.eu,
pavel@...nel.org,
kernel-team@...a.com,
linux-kernel@...r.kernel.org,
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linux-pm@...r.kernel.org
Subject: [RFC PATCH 01/14] swapfile: rearrange functions
Rearrange some functions in preparation for the rest of the series. No
functional change intended.
Signed-off-by: Nhat Pham <nphamcs@...il.com>
---
mm/swapfile.c | 230 +++++++++++++++++++++++++-------------------------
1 file changed, 115 insertions(+), 115 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index df7c4e8b089c..27cf985e08ac 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -124,11 +124,6 @@ static struct swap_info_struct *swap_type_to_swap_info(int type)
return READ_ONCE(swap_info[type]); /* rcu_dereference() */
}
-static inline unsigned char swap_count(unsigned char ent)
-{
- return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */
-}
-
/*
* Use the second highest bit of inuse_pages counter as the indicator
* if one swap device is on the available plist, so the atomic can
@@ -161,6 +156,11 @@ static long swap_usage_in_pages(struct swap_info_struct *si)
/* Reclaim directly, bypass the slot cache and don't touch device lock */
#define TTRS_DIRECT 0x8
+static inline unsigned char swap_count(unsigned char ent)
+{
+ return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */
+}
+
static bool swap_is_has_cache(struct swap_info_struct *si,
unsigned long offset, int nr_pages)
{
@@ -1326,46 +1326,6 @@ static struct swap_info_struct *_swap_info_get(swp_entry_t entry)
return NULL;
}
-static unsigned char __swap_entry_free_locked(struct swap_info_struct *si,
- unsigned long offset,
- unsigned char usage)
-{
- unsigned char count;
- unsigned char has_cache;
-
- count = si->swap_map[offset];
-
- has_cache = count & SWAP_HAS_CACHE;
- count &= ~SWAP_HAS_CACHE;
-
- if (usage == SWAP_HAS_CACHE) {
- VM_BUG_ON(!has_cache);
- has_cache = 0;
- } else if (count == SWAP_MAP_SHMEM) {
- /*
- * Or we could insist on shmem.c using a special
- * swap_shmem_free() and free_shmem_swap_and_cache()...
- */
- count = 0;
- } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) {
- if (count == COUNT_CONTINUED) {
- if (swap_count_continued(si, offset, count))
- count = SWAP_MAP_MAX | COUNT_CONTINUED;
- else
- count = SWAP_MAP_MAX;
- } else
- count--;
- }
-
- usage = count | has_cache;
- if (usage)
- WRITE_ONCE(si->swap_map[offset], usage);
- else
- WRITE_ONCE(si->swap_map[offset], SWAP_HAS_CACHE);
-
- return usage;
-}
-
/*
* When we get a swap entry, if there aren't some other ways to
* prevent swapoff, such as the folio in swap cache is locked, RCU
@@ -1432,6 +1392,46 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry)
return NULL;
}
+static unsigned char __swap_entry_free_locked(struct swap_info_struct *si,
+ unsigned long offset,
+ unsigned char usage)
+{
+ unsigned char count;
+ unsigned char has_cache;
+
+ count = si->swap_map[offset];
+
+ has_cache = count & SWAP_HAS_CACHE;
+ count &= ~SWAP_HAS_CACHE;
+
+ if (usage == SWAP_HAS_CACHE) {
+ VM_BUG_ON(!has_cache);
+ has_cache = 0;
+ } else if (count == SWAP_MAP_SHMEM) {
+ /*
+ * Or we could insist on shmem.c using a special
+ * swap_shmem_free() and free_shmem_swap_and_cache()...
+ */
+ count = 0;
+ } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) {
+ if (count == COUNT_CONTINUED) {
+ if (swap_count_continued(si, offset, count))
+ count = SWAP_MAP_MAX | COUNT_CONTINUED;
+ else
+ count = SWAP_MAP_MAX;
+ } else
+ count--;
+ }
+
+ usage = count | has_cache;
+ if (usage)
+ WRITE_ONCE(si->swap_map[offset], usage);
+ else
+ WRITE_ONCE(si->swap_map[offset], SWAP_HAS_CACHE);
+
+ return usage;
+}
+
static unsigned char __swap_entry_free(struct swap_info_struct *si,
swp_entry_t entry)
{
@@ -1585,25 +1585,6 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry)
unlock_cluster(ci);
}
-void swapcache_free_entries(swp_entry_t *entries, int n)
-{
- int i;
- struct swap_cluster_info *ci;
- struct swap_info_struct *si = NULL;
-
- if (n <= 0)
- return;
-
- for (i = 0; i < n; ++i) {
- si = _swap_info_get(entries[i]);
- if (si) {
- ci = lock_cluster(si, swp_offset(entries[i]));
- swap_entry_range_free(si, ci, entries[i], 1);
- unlock_cluster(ci);
- }
- }
-}
-
int __swap_count(swp_entry_t entry)
{
struct swap_info_struct *si = swp_swap_info(entry);
@@ -1717,57 +1698,6 @@ static bool folio_swapped(struct folio *folio)
return swap_page_trans_huge_swapped(si, entry, folio_order(folio));
}
-static bool folio_swapcache_freeable(struct folio *folio)
-{
- VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
-
- if (!folio_test_swapcache(folio))
- return false;
- if (folio_test_writeback(folio))
- return false;
-
- /*
- * Once hibernation has begun to create its image of memory,
- * there's a danger that one of the calls to folio_free_swap()
- * - most probably a call from __try_to_reclaim_swap() while
- * hibernation is allocating its own swap pages for the image,
- * but conceivably even a call from memory reclaim - will free
- * the swap from a folio which has already been recorded in the
- * image as a clean swapcache folio, and then reuse its swap for
- * another page of the image. On waking from hibernation, the
- * original folio might be freed under memory pressure, then
- * later read back in from swap, now with the wrong data.
- *
- * Hibernation suspends storage while it is writing the image
- * to disk so check that here.
- */
- if (pm_suspended_storage())
- return false;
-
- return true;
-}
-
-/**
- * folio_free_swap() - Free the swap space used for this folio.
- * @folio: The folio to remove.
- *
- * If swap is getting full, or if there are no more mappings of this folio,
- * then call folio_free_swap to free its swap space.
- *
- * Return: true if we were able to release the swap space.
- */
-bool folio_free_swap(struct folio *folio)
-{
- if (!folio_swapcache_freeable(folio))
- return false;
- if (folio_swapped(folio))
- return false;
-
- delete_from_swap_cache(folio);
- folio_set_dirty(folio);
- return true;
-}
-
/**
* free_swap_and_cache_nr() - Release reference on range of swap entries and
* reclaim their cache if no more references remain.
@@ -1842,6 +1772,76 @@ void free_swap_and_cache_nr(swp_entry_t entry, int nr)
put_swap_device(si);
}
+void swapcache_free_entries(swp_entry_t *entries, int n)
+{
+ int i;
+ struct swap_cluster_info *ci;
+ struct swap_info_struct *si = NULL;
+
+ if (n <= 0)
+ return;
+
+ for (i = 0; i < n; ++i) {
+ si = _swap_info_get(entries[i]);
+ if (si) {
+ ci = lock_cluster(si, swp_offset(entries[i]));
+ swap_entry_range_free(si, ci, entries[i], 1);
+ unlock_cluster(ci);
+ }
+ }
+}
+
+static bool folio_swapcache_freeable(struct folio *folio)
+{
+ VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+
+ if (!folio_test_swapcache(folio))
+ return false;
+ if (folio_test_writeback(folio))
+ return false;
+
+ /*
+ * Once hibernation has begun to create its image of memory,
+ * there's a danger that one of the calls to folio_free_swap()
+ * - most probably a call from __try_to_reclaim_swap() while
+ * hibernation is allocating its own swap pages for the image,
+ * but conceivably even a call from memory reclaim - will free
+ * the swap from a folio which has already been recorded in the
+ * image as a clean swapcache folio, and then reuse its swap for
+ * another page of the image. On waking from hibernation, the
+ * original folio might be freed under memory pressure, then
+ * later read back in from swap, now with the wrong data.
+ *
+ * Hibernation suspends storage while it is writing the image
+ * to disk so check that here.
+ */
+ if (pm_suspended_storage())
+ return false;
+
+ return true;
+}
+
+/**
+ * folio_free_swap() - Free the swap space used for this folio.
+ * @folio: The folio to remove.
+ *
+ * If swap is getting full, or if there are no more mappings of this folio,
+ * then call folio_free_swap to free its swap space.
+ *
+ * Return: true if we were able to release the swap space.
+ */
+bool folio_free_swap(struct folio *folio)
+{
+ if (!folio_swapcache_freeable(folio))
+ return false;
+ if (folio_swapped(folio))
+ return false;
+
+ delete_from_swap_cache(folio);
+ folio_set_dirty(folio);
+ return true;
+}
+
#ifdef CONFIG_HIBERNATION
swp_entry_t get_swap_page_of_type(int type)
--
2.47.1
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